1. Field of the Invention
The present invention relates to an actuator of a rotary resonance type and an electric beauty appliance.
2. Description of Related Art
Electric toothbrushes as electric beauty appliances known in the art include a bass brushing toothbrush that is contacted obliquely with a boundary between teeth and gums (at an angle of approximately 45 degrees) and vibrated laterally by reciprocal linear motion; and a rolling brushing toothbrush that rotates reciprocally (in forward and reverse directions) about a shaft within a predetermined angular range in such a manner that the toothbrush moves from gums to teeth and vice versa in a rotational manner.
For driving these toothbrushes, many structures have been used for converting the typical rotary motion of a rotary DC motor into a reciprocal linear or rotary motion, via a motion direction converting mechanism. Furthermore, besides these structures, structures are known wherein the toothbrush is moved reciprocally linearly by means of a linear drive actuator, or the toothbrush is rotated reciprocally by making a resonance vibrating mechanism, which is separated from a drive source including an actuator, resonate by the vibration of the actuator.
In a structure wherein a toothbrush is moved reciprocally linearly by means of a linear drive actuator, as shown in Japanese Patent Application Laid-Open No. 2002-078310, the linear drive actuator directly produces reciprocal vibration in the axial direction of an output shaft that is directly connected to a brush part so as to realize bass brushing. This configuration generates no power loss due to a motion converting mechanism thus enabling fast vibration.
Furthermore, a structure having an actuator and a resonance vibrating mechanism separated from a drive source including the actuator is disclosed in a vibration toothbrush disclosed in Japanese Patent No. 3243529. Japanese Patent No. 3243529 realizes rolling brushing by vibrating the resonance vibrating mechanism having a lever arm by a drive section with an electro magnet and a permanent magnet and moving the lever arm that is coaxially connected to a toothbrush part in swinging motion.
Thus, as an actuator to be used for an electric toothbrush and produce reciprocal rotary motion, there remains in the art a need for a high-power actuator with a simpler structure.